Musannaf Ibn Abi Shayba 19:466

Abu Bakr narrated to us, he said: Ibn Idris narrated to us, from Hisham, from al-Hasan and Ibn Sirin: They used to, when asked about a man who has intercourse with his wife’s slave-girl, recite this verse: "And they who guard their private parts, except from their wives or those their right hands possess, for indeed, they are not to be blamed."